The present invention relates generally to a die for profile extrusion. More particularly, the invention relates to an improved die for profile extrusion which is applicable, although not exclusively, to the molding of a weatherstrip having a hollow shielding portion of which the height varies along the longitudinal direction thereof.
A typical extrusion molding produces an article having the same profile successively throughout the extrusion molding operation. For example, in the extrusion molding for a weatherstrip comprised of a welt and a semicylindrical, hollow shielding portion, the geometry of the extruded product, especially of the hollow shielding portion and portions thereof connected to the welt, is fixed. Tight shielding of a weatherstrip for opening corners of a vehicle or for uneven counter parts for example tends to require a weatherstrip including a shielding portion which has varying heights.
Recently, profile extrusion molding has been developed which is adapted for changing the location of an outlet port of a die during an extrusion molding operation to form a profile product having a different geometry thereof.
Japanese Pat. First Publication (tokkaisho) No. 59-171735 discloses an improved die assembly for profile extrusion which is available to form a weatherstrip. The die assembly comprises a stationary die and a movable die and is adapted for varying the connecting positions of a hollow shielding portion to a welt of the weatherstrip. The movable die includes a C-shaped outlet port for defining the hollow shielding portion, while the stationary die includes a straight shaped outlet port for defining the welt and a material feed path for the C-shaped outlet port of the movable die. The movable die further includes a material feed cavity for the C-shaped outlet port which communicates with the material feed path of the stationary die. With the structure of this die assembly, the movable die is slidable with respect to the stationary die to vary the connecting positions of the hollow shielding portion to the welt over the width of the latter. It will be thus noted that a weatherstrip may be obtained including a welt and a hollow shielding portion of which the connecting position to the welt is varied.
However, in a weatherstrip for a vehicle for example, a hollow shielding portion having a different height from a welt is necessary in order to obtain tight shielding applicable to long parts having a different height in the longitudinal direction.